JP5224159B2 - Surface emitting laser array, optical scanning device, and image forming apparatus - Google Patents

Description

  The present invention relates to a surface emitting laser array, an optical scanning apparatus, and an image forming apparatus. More specifically, the present invention relates to a surface emitting laser array having a plurality of surface emitting laser elements, an optical scanning apparatus having the surface emitting laser array, and the The present invention relates to an image forming apparatus including an optical scanning device.

  In image recording in electrophotography, an image forming method using a laser is widely known as an image forming means for obtaining high-definition image quality. In the case of electrophotography, a method in which a latent image is formed by rotating a drum (sub-scanning the laser) while scanning the laser (main scanning) using a polygon mirror in the axial direction of a photosensitive drum. Is.

  In the field of electrophotography, there is a demand for high-definition images and high-speed output. In order to increase the definition of an image, when the resolution of the image is doubled, twice the time is required for both main scanning and sub-scanning. Therefore, four times the time is required for image output. Therefore, in order to realize high definition of images, it is necessary to simultaneously achieve high speed image output.

  As a method for realizing high-speed image output, it is conceivable to increase the output of the laser, increase the number of beams, increase the sensitivity of the photoconductor, and the like. Among them, in a high-speed output machine, it is common to use a multi-beam writing light source. Compared to the case of using one laser, when n lasers are used at the same time, the latent image forming area is n times, and the time required for image formation is 1 / n.

  As such an example, a multi-beam semiconductor laser having a plurality of light emitting light sources on one chip has been proposed (Patent Documents 1 and 2). These are configurations using edge emitting semiconductor lasers, and are one-dimensionally arranged, and multi-beam increases power consumption and requires a cooling system. The degree is the limit. Further, when the number of beams is increased, the amount of deviation of the beam from the optical axis of the optical element of the optical system increases, and the optical characteristics deteriorate.

  On the other hand, a surface emitting laser is a semiconductor laser that emits light in a direction perpendicular to a substrate and can be easily two-dimensionally integrated. In addition, the surface emitting laser has power consumption that is about an order of magnitude smaller than that of the edge type laser, and is advantageous for integrating more light sources in two dimensions.

  As an example of a writing optical system that scans using a polygon mirror, a surface emitting laser array composed of 36 surface emitting laser elements arranged in 6 rows × 6 columns is known (Patent Documents 3 and 4).

  In this surface emitting laser array, six surface emitting laser elements are arranged in the sub-scanning direction, and six surface emitting laser elements are arranged in the main scanning direction. The interval between the six surface emitting laser elements arranged in the sub-scanning direction (drum rotating direction) is d, and the six surface emitting laser elements arranged in the main scanning direction (longitudinal direction of the drum) are d. The interval is x, and the intervals in the sub-scanning direction of the six perpendiculars drawn from the six centers of the six surface emitting laser elements arranged in the sub-scanning direction to the straight line arranged in the sub-scanning direction are equal. 36 surface emitting laser elements are arranged so as to be (d / 6).

  In the case where 36 laser beams emitted from the 36 surface emitting laser elements arranged in this way are collected by one collimating lens, all the laser beams are optical axes of the collimating lens in consideration of lens aberration. It is desirable to concentrate in the vicinity. That is, it is preferable to arrange the individual surface emitting laser elements constituting the surface emitting laser array arranged two-dimensionally with the highest degree of integration. From such a request, a proposal for increasing the arrangement density of a plurality of surface emitting laser elements has been made (Patent Document 5). And in patent document 5, the some surface emitting laser element is arrange | positioned by the fixed space | interval.

JP 11-340570 A JP 11-354888 A JP 2005-274755 A JP 2005-234510 A JP 2001-272615 A

  However, when a plurality of surface-emitting laser elements are integrated at a high density, heat generated from the surface-emitting laser elements is mutually exchanged between the surface-emitting laser elements in the surface-emitting laser array as the interval between adjacent surface-emitting laser elements decreases. This causes various problems such as a decrease in output and a decrease in reliability.

  That is, in the surface emitting laser array, since a plurality of surface emitting laser elements are two-dimensionally arranged, the surface emitting laser element near the center is more influenced by other surface emitting laser elements, and the surface emitting laser element is more affected. The surface emitting laser elements arranged at the center of the array have a greater output drop due to temperature rise, and are operated simultaneously under the condition that all surface emitting laser elements emit uniformly based on the characteristics when operated individually. However, there is a problem that the output characteristics are distributed in the surface emitting laser array. Further, since the lifetime of the surface emitting laser element is shorter as the temperature is higher, the lifetime as the surface emitting laser array is regulated by the lifetime of the surface emitting laser element arranged near the center and becomes shorter.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a surface emitting laser array capable of uniformizing the characteristics of a plurality of surface emitting laser elements when simultaneously operated in the array. That is.

  Another object of the present invention is to provide a surface emitting laser array capable of extending the lifetime.

  Furthermore, another object of the present invention is to provide an optical scanning device having a surface emitting laser array capable of uniformizing the characteristics of a plurality of surface emitting laser elements when operated simultaneously in the array.

  Furthermore, another object of the present invention is to provide an optical scanning device having a surface emitting laser array capable of extending the lifetime.

  Furthermore, another object of the present invention is to provide an image forming apparatus provided with a surface emitting laser array capable of making the characteristics of a plurality of surface emitting laser elements uniform when operated simultaneously in the array.

  Furthermore, another object of the present invention is to provide an image forming apparatus including a surface emitting laser array capable of extending the lifetime.

The present invention is, to a first aspect, a surface emitting laser array Ru comprising a surface-emitting laser element of the multiple, the plurality of surface emitting laser elements, at least two surface-emission arranged in a first direction A plurality of element arrays each including a laser element are two-dimensionally arranged so as to be aligned in a second direction perpendicular to the first direction, and the plurality of surface emitting laser elements are equally spaced with respect to the first direction. , and the interval in the first or second direction of the surface-emitting laser element before Kifuku number of central portion than the peripheral portion of the surface emitting laser array is wider surface emitting laser array.

  In this specification, the interval between the surface emitting laser elements means the distance between the centers of the two surface emitting laser elements.

Preferably, the interval between the at least two surface emitting laser elements arranged in the first direction is wider in the central portion than in the peripheral portion of the surface emitting laser array.

Preferably, the interval between the at least two surface emitting laser elements arranged in the first direction is further different depending on the position in the first direction.

Preferably, spacing definitive in the second direction of the plurality of element rows are wider central portion than the peripheral portion of the surface emitting laser array.

Preferably, spacing definitive in the second direction of the plurality of element rows are further differs depending on the position in the second direction.

Preferably, an interval of at least two surface-emission laser device arranged in the first direction has a wider central portion than the peripheral portion of the surface emitting laser array, spacing definitive in the second direction of the plurality of element arrays, The central part is wider than the peripheral part of the surface emitting laser array.

Preferably, an interval of at least two surface-emission laser device arranged in the first direction, further depends on the location in the first direction, spacing definitive in the second direction of the plurality of element rows are further second It depends on the position in the direction.

  Preferably, the first direction is a sub-scanning direction when the surface emitting laser array is used in an optical scanning device, and the second direction is when the surface emitting laser array is used in an optical scanning device. In the main scanning direction.

  According to a second aspect of the present invention, there is provided a surface emitting laser array in which a plurality of surface emitting laser elements are two-dimensionally arranged, and includes at least two arranged in a line along a first direction. A plurality of element arrays composed of surface emitting laser elements are arranged in a second direction perpendicular to the first direction, and the plurality of surface emitting laser elements are equally spaced with respect to the first direction. 2, an interval between two element rows located in the center of the plurality of rows and adjacent to each other is larger than an interval between two element rows located on the end side of the plurality of rows and adjacent to each other. This is a surface emitting laser array characterized in that the number of is larger than the number of surface emitting laser elements constituting one element row.

  According to a third aspect of the present invention, there is provided a surface emitting laser array in which a plurality of surface emitting laser elements are two-dimensionally arranged, wherein a density at which the surface emitting laser elements are arranged is equal to the surface emitting laser. The surface emitting laser array is characterized in that the central portion is sparser than the peripheral portion of the array.

  According to a fourth aspect of the present invention, there is provided an optical scanning device that scans a surface to be scanned with light, the light source unit having the surface emitting laser array of the present invention; and the deflection for deflecting the light from the light source unit. And a scanning optical system for condensing the light deflected by the polarizer onto the surface to be scanned.

  According to a fifth aspect of the present invention, there is provided at least one image carrier; and at least one optical scanning device according to the invention that scans light including image information on the at least one image carrier. An image forming apparatus provided.

  From a sixth viewpoint, the present invention is an image forming apparatus including the surface emitting laser array of the present invention as a writing light source.

  According to the present invention, the interval between the surface emitting laser elements arranged in the central portion of the surface emitting laser array is wider than the interval between the surface emitting laser elements arranged in the peripheral portion of the surface emitting laser array. As a result, when a plurality of surface emitting laser elements are operated simultaneously, the heat generated from the surface emitting laser elements arranged in the peripheral portion of the surface emitting laser array has an effect on the surface emitting laser elements arranged in the central portion. The temperature rise of the surface emitting laser element that is reduced and arranged in the center is reduced as compared with the case where a plurality of surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction.

  Therefore, according to the present invention, the output characteristics of the plurality of surface emitting laser elements can be made uniform in the surface emitting laser array. In addition, since the temperature of the surface emitting laser element having the highest temperature in the surface emitting laser array is lowered, the lifetime of the surface emitting laser array can be extended.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is a plan view of a surface emitting laser array according to Embodiment 1 of the present invention. Referring to FIG. 1, a surface emitting laser array 100 according to Embodiment 1 includes surface emitting laser elements 1 to 36.

  The surface emitting laser elements 1 to 36 are two-dimensionally arranged in 6 rows × 6 columns. And six surface emitting laser elements 1, 7, 13, 19, 25, 31/2, 8, 14, 20, 26, 32/3, 9, 15, 21, 27, 33/4, 10, 16 , 22, 28, 34/5, 11, 17, 23, 29, 35/6, 12, 18, 24, 30, 36 are arranged in the sub-scanning direction, and include six surface emitting laser elements 1-6 / 7-12 / 13-18 / 14-24 / 25-30 / 31-36 are arranged in the main scanning direction.

  Six surface emitting laser elements 1 to 6/7 to 12/13 to 18/14 to 24/25 to 30/31 to 36 arranged in the main scanning direction are arranged stepwise in the sub scanning direction. Is done. As a result, the 36 laser beams emitted from the 36 surface emitting laser elements 1 to 36 do not overlap each other.

  In the six surface emitting laser elements 1 to 6/7 to 12/13 to 18/14 to 24/25 to 30/31 to 36 arranged in the main scanning direction, the distance between two adjacent surface emitting laser elements Is set to the interval X1 in the central portion of the surface emitting laser array 100, and is set to the interval X2 (<X1) in the peripheral portion. That is, the intervals between the surface emitting laser elements 3, 4, 9, 10, 15, 16, 21, 22, 27, 28, 33, 34 arranged at the center of the surface emitting laser array 100 are The surface-emitting laser elements 1, 2, 5, 6, 7, 8, 11, 12, 13, 14, 17, 17 set to the interval X 1 The interval between 18/19, 20/23, 24/25, 26/29, 30/31, 32/35, 36 is set to the interval X2. Also, between surface emitting laser elements 2, 3/4, 5/5/8, 9/10, 11/14, 15/16, 17/20, 21/22, 23/26, 27 The interval between / 28, 29/32, 33/34, 35 is set to an interval X3 between the interval X1 and the interval X2.

  In this case, the interval X1 is set to an interval wider than the interval when 36 surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction, and the interval X2 is set to 36 surface emitting lasers. The interval is set smaller than the interval when the elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction. The interval X1 is set to 50 μm, for example, the interval X2 is set to 25 μm, for example, and the interval X3 is set to 35 μm, for example.

  Further, six surface emitting laser elements 1, 7, 13, 19, 25, 31/2, 8, 14, 20, 26, 32/3, 9, 15, 21, 27, arranged in the sub-scanning direction. 33/4, 10, 16, 22, 28, 34/5, 11, 17, 23, 29, 35/6, 12, 18, 24, 30, 36, the distance between two adjacent surface emitting laser elements Is constant in the sub-scanning direction and is set to the interval d. For example, d is set to d = 30 μm.

  An interval C in the sub-scanning direction of six perpendicular lines L1 to L6 drawn from six centers of the six surface emitting laser elements 1 to 6 arranged in the main scanning direction to a straight line 40 arranged in the sub-scanning direction is , Equally spaced and determined by C = d / 6. In the example shown in FIG. 1, C = 30/6 = 5 μm.

  Subordinates of six perpendicular lines drawn from six centers of six surface emitting laser elements 7 to 12/13 to 18/19 to 24/25 to 30/31 to 36 arranged in the main scanning direction on a straight line 40 The intervals in the scanning direction are also equal intervals and the same as the interval C.

  Thus, in the surface emitting laser array 100, the six surface emitting laser elements 1, 7, 13, 19, 25, 31/2, 8, 14, 20, 26, 32/32 arranged in the sub-scanning direction. 3, 9, 15, 21, 27, 33/4, 10, 16, 22, 28, 34/5, 11, 17, 23, 29, 35/6, 12, 18, 24, 30, 36, etc. The six surface emitting laser elements 1 to 6/7 to 12/13 to 18/14 to 24/25 to 30/31 to 36 arranged at the interval d in the main scanning direction are the surface emitting laser array 100. It arrange | positions so that it may become large as it goes to a center part from the peripheral part of.

  That is, in the surface emitting laser array 100, the interval between the six surface emitting laser elements 1 to 6/7 to 12/13 to 18/14 to 24/25 to 30/31 to 36 arranged in the main scanning direction is as follows. The central portion is wider than the peripheral portion of the surface emitting laser array 100 and differs depending on the position in the main scanning direction.

  As a specific example, the interval between the surface emitting laser elements 13-14 (peripheral portion) is narrower than the interval between the surface emitting laser elements 15-16 (central portion). Further, the interval between the surface emitting laser elements 26-31 (peripheral portion) is narrower than the interval between the surface emitting laser elements 16-21 (central portion).

  As a result, the influence of heat generated from the surface emitting laser elements arranged in the peripheral portion of the surface emitting laser array 100 on the surface emitting laser elements arranged in the central portion is reduced. When the surface emitting laser elements 1 to 36 are simultaneously operated, the temperature distribution in the surface emitting laser array 100 is larger than that in the case where 36 surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction. It is made uniform. Therefore, the output characteristics of the 36 surface emitting laser elements can be made uniform. Since the temperatures of the surface emitting laser elements 15, 16, 21, and 22 that are the highest temperature in the surface emitting laser array 100 are lowered, the lifetime of the surface emitting laser array 100 can be extended.

  The interval X1 is set to be wider than the interval when 36 surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction, and the interval X2 is set to 36 Since the surface emitting laser elements are set to an interval smaller than the interval when the surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction, the area occupied by the surface emitting laser elements 1 to 36 is 36 surface emitting laser elements. Can be made smaller than when they are arranged at equal intervals in the sub-scanning direction and the main scanning direction. As a result, when the surface emitting laser array 100 is used as a light source for optical writing, 36 surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction with respect to aberrations of an optical system such as a collimating lens. It can be smaller than the case. And since the temperature rise of the surface emitting laser elements 15, 16, 21, and 22 near the center can be suppressed while the area of the surface emitting laser array 100 is reduced, the influence of the aberration of the optical system such as a lens can be suppressed. When the surface emitting laser array 100 is used in an image forming apparatus, a clear image is obtained and the life of the surface emitting laser array 100 can be extended, so that the optical writing optical unit itself can be reused, and the environmental load is reduced. Can contribute.

  In the main scanning direction, the interval between two adjacent surface emitting laser elements differs depending on the position in the main scanning direction, and the interval between the surface emitting laser elements arranged in the sub scanning direction is constant. In principle, the six surface emitting laser elements 1 to 6/7 to 12/13 to 18/19 to 24/25 to 30/31 to 36 are arranged in an S-curve shape in the main scanning direction.

FIG. 2 is a schematic cross-sectional view of the surface emitting laser element 1 shown in FIG. Referring to FIG. 2, the surface emitting laser element 1 includes a substrate 101, reflection layers 102 and 106, resonator spacer layers 103 and 105, an active layer 104, a selective oxidation layer 107, a contact layer 108, A SiO ₂ layer 109, an insulating resin 110, a p-side electrode 111, and an n-side electrode 112 are provided.

The substrate 101 is made of n-type gallium arsenide (n-GaAs). The reflective layer 102 has an n-Al _0.9 Ga _0.1 As / n-Al _0.3 Ga _0.7 As pair with a period of 40.5 [n-Al _0.9 Ga. _0.1 As / n-Al _0.3 Ga _0.7 As] and is formed on one main surface of the substrate 101. The film thicknesses of n-Al _0.9 Ga _0.1 As and n-Al _0.3 Ga _0.7 As are λ / 4n (where the oscillation wavelength of the surface-emitting laser element 1 is λ. n is the refractive index of each semiconductor layer.

The resonator spacer layer 103 is made of non-doped Al _0.6 Ga _0.4 As and is formed on the reflective layer 102. The active layer 104 has a quantum well structure including a well layer made of Al _0.12 Ga _0.88 As and a barrier layer made of Al _0.3 Ga _0.7 As, and is formed on the resonator spacer layer 103. It is formed.

The resonator spacer layer 105 is made of non-doped Al _0.6 Ga _0.4 As and is formed on the active layer 104. The reflective layer 106 has [p-Al _0.9 Ga _0.1 As of 24 periods when a pair of p-Al _0.9 Ga _0.1 As / Al _0.3 Ga _0.7 As is taken as one period. / Al _0.3 Ga _0.7 As] and formed on the resonator spacer layer 105. The film thickness of each of p-Al _0.9 Ga _0.1 As and p-Al _0.3 Ga _0.7 As is λ / 4n (n is the refractive index of each semiconductor layer).

  The selective oxidation layer 107 is made of p-AlAs and is provided in the reflection layer 106. The selective oxidation layer 107 includes a non-oxidized region 107a and an oxidized region 107b, and has a thickness of 20 nm.

The contact layer 108 is made of p-GaAs and is formed on the reflective layer 106. The SiO ₂ layer 109 includes one main surface of a part of the reflective layer 102 and end faces of the resonator spacer layer 103, the active layer 104, the resonator spacer layer 105, the reflective layer 106, the selective oxidation layer 107, and the contact layer 108. It is formed to cover.

The insulating resin 110 is formed in contact with the SiO ₂ layer 109. The p-side electrode 111 is formed on part of the contact layer 108 and the insulating resin 110. The n-side electrode 112 is formed on the back surface of the substrate 101.

  Each of the reflective layers 102 and 106 constitutes a semiconductor distributed Bragg reflector that reflects the oscillation light oscillated in the active layer 104 by Bragg multiple reflection and confines it in the active layer 104.

  The oxidized region 107b has a smaller refractive index than the non-oxidized region 107a. The oxidized region 107b constitutes a current confinement part that restricts the path through which the current injected from the p-side electrode 111 flows to the active layer 104 to the non-oxidized region 107a, and also oscillates the oscillation light oscillated in the active layer 104. Confine in the region 107a. Thus, the surface emitting laser element 1 can oscillate with a low threshold current.

FIG. 3 is a sectional view showing the vicinity of the active layer 104 of the surface emitting laser element 1 shown in FIG. Referring to FIG. 3, the reflective layer 102 includes a low refractive index layer 1021, a high refractive index layer 1022, and a composition gradient layer 1023. The low refractive index layer 1021 is made of n-Al _0.9 Ga _0.1 As, and the high refractive index layer 1022 is made of n-Al _0.3 Ga _0.7 As. The composition gradient layer 1023 is made of n-AlGaAs in which the Al composition gradually changes from one of the low refractive index layer 1021 and the high refractive index layer 1022 to the other. The low refractive index layer 1021 is in contact with the resonator spacer layer 103.

The reflective layer 106 includes a low refractive index layer 1061, a high refractive index layer 1062, and a composition gradient layer 1063. The low refractive index layer 1061 is made of p-Al _0.9 Ga _0.1 As, and the high refractive index layer 1062 is made of n-Al _0.3 Ga _0.7 As. The composition gradient layer 1063 is made of p-AlGaAs in which the Al composition gradually changes from one of the low refractive index layer 1061 and the high refractive index layer 1062 to the other. The low refractive index layer 1061 is in contact with the resonator spacer layer 105.

The active layer 104 includes three well layers 1041 each made of Al _0.12 Ga _0.88 As and four barrier layers 1042 each made of Al _0.3 Ga _0.7 As alternately stacked. A quantum well structure. The barrier layer 1042 is in contact with the resonator spacer layers 103 and 105.

  In the surface emitting laser element 1, the resonator spacer layers 103 and 105 and the active layer 104 constitute a resonator, and the thickness of the resonator in the direction perpendicular to the substrate 101 is equal to one wavelength of the surface emitting laser element 1 ( = Λ). That is, the resonator spacer layers 103 and 105 and the active layer 104 constitute a one-wavelength resonator.

  Each of the surface emitting laser elements 2 to 36 shown in FIG. 1 has the same configuration as that of the surface emitting laser element 1 shown in FIGS.

  4, 5 and 6 are first to third process diagrams showing a method of manufacturing the surface emitting laser array 100 shown in FIG. In the description of FIGS. 4 to 6, the surface emitting laser array 100 of the surface emitting laser array 100 is referred to with reference to the process of manufacturing one surface emitting laser element among the 36 surface emitting laser elements 1 to 36 shown in FIG. 1. A manufacturing method will be described.

  Referring to FIG. 4, when a series of operations is started, a reflective layer 102, a resonator spacer layer 103, an active layer 104, a resonance layer are formed using metal organic chemical vapor deposition (MOCVD). A vessel spacer layer 105, a reflective layer 106, a selective oxidation layer 107, and a contact layer 108 are sequentially stacked on the substrate 101 (see step (a) in FIG. 4).

In this case, n-Al _0.9 Ga _0.1 As and n-Al _0.3 Ga _0.7 As of the reflective layer 102 are changed from trimethylaluminum (TMA), trimethylgallium (TMG), arsine (AsH ₃ ), and selenium. Hydrogen fluoride (H ₂ Se) is formed as a raw material, and Al _0.6 Ga _0.4 As of the resonator spacer layer 103 is formed from trimethyl aluminum (TMA), trimethyl gallium (TMG), and arsine (AsH ₃ ). To do.

Further, Al _0.12 Ga _0.88 As / Al _0.3 Ga _0.7 As for the active layer 104 is formed using trimethylaluminum (TMA), trimethylgallium (TMG), and arsine (AsH ₃ ) as raw materials.

Further, Al _0.6 Ga _0.4 As for the resonator spacer layer 105 is formed using trimethylaluminum (TMA), trimethylgallium (TMG), and arsine (AsH ₃ ) as raw materials.

_{Further, p-Al 0.9 Ga 0.1 As} / p-Al 0.3 Ga 0.7 As trimethylaluminum reflective layer 106 (TMA), trimethyl gallium (TMG), arsine (AsH ₃₎ and tetrabromide Carbonized carbon (CBr ₄ ) is used as a raw material. Note that dimethyl zinc (DMZn) may be used instead of carbon tetrabromide (CBr ₄ ).

Further, p-AlAs for the selective oxidation layer 107 is formed using trimethylaluminum (TMA), arsine (AsH ₃ ), and carbon tetrabromide (CBr ₄ ) as raw materials, and p-GaAs for the contact layer 108 is trimethylgallium (TMG). , Arsine (AsH ₃ ) and carbon tetrabromide (CBr ₄ ). Also in this case, dimethyl zinc (DMZn) may be used instead of carbon tetrabromide (CBr ₄ ).

  Thereafter, a resist is applied on the contact layer 108, and a resist pattern 120 is formed on the contact layer 108 using a photoengraving technique (see step (b) in FIG. 4).

  When the resist pattern 120 is formed, using the formed resist pattern 120 as a mask, the reflective layer 102, the resonator spacer layer 103, the active layer 104, the resonator spacer layer 105, the reflective layer 106, the selective oxidation layer 107, and the contact layer are formed. The peripheral portion of 108 is removed by dry etching, and the resist pattern 120 is further removed (see step (c) in FIG. 4).

  Next, referring to FIG. 5, after the step (c) shown in FIG. 4, the sample is heated to 425 ° C. in an atmosphere in which water heated to 85 ° C. is bubbled with nitrogen gas, thereby selectively oxidizing layer 107. Is oxidized from the outer peripheral portion toward the central portion to form a non-oxidized region 107a and an oxidized region 107b in the selective oxidation layer 107 (see step (d) in FIG. 5).

Thereafter, a SiO ₂ layer 109 is formed on the entire surface of the sample by using a chemical vapor deposition (CVD) method, and a region serving as a light emitting portion and a surrounding SiO ₂ layer using a photoengraving technique. 109 is removed (see step (e) in FIG. 5).

  Next, the insulating resin 110 is applied to the entire sample by spin coating, and the insulating resin 110 on the region to be the light emitting portion is removed (see step (f) in FIG. 5).

  Referring to FIG. 6, after forming insulating resin 110, a resist pattern having a predetermined size is formed on a region serving as a light emitting portion, and a p-side electrode material is formed on the entire surface of the sample by vapor deposition. The p-side electrode material on the pattern is removed by lift-off to form the p-side electrode 111 (see step (g) in FIG. 6). Then, the back surface of the substrate 101 is polished, an n-side electrode 112 is formed on the back surface of the substrate 101, and further annealed to establish ohmic conduction between the p-side electrode 111 and the n-side electrode 112 (step (h) in FIG. 6). reference). Thereby, the surface emitting laser array 100 is completed.

  Note that, in the steps (b) and (c) shown in FIG. 4, dry etching for forming one surface emitting laser element is illustrated, but actually, the steps (b) and (c) In FIG. 1, dry etching is performed to simultaneously form the 36 surface emitting laser elements 1 to 36 shown in FIG. In this case, the resist pattern for simultaneously forming the 36 surface emitting laser elements 1 to 36 is formed using a photomask suitable for the arrangement of the 36 surface emitting laser elements 1 to 36 shown in FIG. . That is, the resist pattern for simultaneously forming the 36 surface emitting laser elements 1 to 36 is set such that the intervals X1, X2, and X3 in the main scanning direction satisfy the interval X2 <X3 <X1. Six perpendicular lines drawn from 6 centers of 6 surface emitting laser elements 1-6 / 7 to 12/13 to 18/19 to 24/25 to 30/31 to 36 arranged in a direction on a straight line 40 It is formed using a photomask designed so that L1 to L6 are equally spaced C.

  FIG. 7 is another schematic cross-sectional view of the surface emitting laser elements 1 to 36 shown in FIG. Each of the surface emitting laser elements 1 to 36 shown in FIG. 1 may be composed of the surface emitting laser element 1A shown in FIG.

  Referring to FIG. 7, in surface emitting laser element 1A, resonator spacer layers 103 and 105 of surface emitting laser element 1 shown in FIG. 2 are replaced with resonator spacer layers 103A and 105A, respectively, and active layer 104 is replaced with active layer 104A. The others are the same as those of the surface emitting laser element 1.

The resonator spacer layer 103 </ b> A is made of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and is formed on the reflective layer 102. The active layer 104A has a quantum well structure including a well layer made of GaInPAs having a compressive strain composition and a barrier layer made of Ga _0.6 In _0.4 P having tensile strain, and is formed on the resonator spacer layer 103A. It is formed. The resonator spacer layer 105A is made of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and is formed on the active layer 104A. The surface emitting laser element 1A oscillates a 780 nm laser beam.

  FIG. 8 is a cross-sectional view showing the vicinity of the active layer 104A of the surface emitting laser element 1A shown in FIG. Referring to FIG. 8, low refractive index layer 1021 of reflective layer 102 is in contact with resonator spacer layer 103A, and low refractive index layer 1061 of reflective layer 106 is in contact with resonator spacer layer 105A.

The active layer 104A has a quantum well structure in which three well layers 1041A each made of GaInPAs and four barrier layers 1042A each made of Ga _0.6 In _0.4 P are alternately stacked. The barrier layer 1042A is in contact with the resonator spacer layers 103A and 105A.

  In the surface emitting laser element 1A, the resonator spacer layers 103A and 105A and the active layer 104A constitute a resonator, and the thickness of the resonator in the direction perpendicular to the substrate 101 is 1 of that of the surface emitting laser element 1A. Wavelength (= λ) is set. That is, the resonator spacer layers 103A and 105A and the active layer 104A constitute a one-wavelength resonator.

  Table 1 shows that the cavity spacer layers 103A and 105A and the wells in the case where the well layers 1041A of the resonator spacer layers 103A and 105A / active layer 104A are made of AlGaAs / AlGaAs and AlGaInP / GaInPAs, respectively. The difference in band gap between the layer 1041A and the difference in band gap between the barrier layer 1042A and the well layer 1041A is shown.

  When AlGaAs and AlGaAs are used for the cavity spacer layers 103A and 105A and the well layer 1041A of the active layer 104A, respectively, the bands of the cavity spacer layers 103A and 105A and the well layer 1041A in the surface emitting laser element having an oscillation wavelength of 780 nm. The difference in gap is 465.9 meV, and the difference in band gap between the barrier layer 1042A and the well layer 1041A is 228.8 meV.

  When AlGaAs and AlGaAs are used for the cavity spacer layers 103A and 105A and the well layer 1041A of the active layer 104A, respectively, the cavity spacer layers 103A and 105A and the well layer 1041A in the surface emitting laser element having an oscillation wavelength of 850 nm The difference in the band gap is 602.6 meV, and the difference in the band gap between the barrier layer 1042A and the well layer 1041A is 365.5 meV.

  On the other hand, when AlGaInP and GaInPAs are used for the well layers 1041A of the cavity spacer layers 103A and 105A and the active layer 104A, respectively, the cavity spacer layers 103A and 105A and the well layer 1041A in the surface emitting laser element 1A having an oscillation wavelength of 780 nm. The band gap difference between the barrier layer 1042A and the well layer 1041A is 463.3 meV.

The surface emitting laser element 1A is manufactured according to steps (a) to (h) shown in FIGS. In this case, in step (a), (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P constituting the resonator spacer layers 103A and 105A is changed to trimethylaluminum (TMA), trimethylgallium (TMG), Trimethylindium (TMI) and phosphine (PH ₃ ) are used as raw materials, and GaInPAs constituting the well layer 1041A of the active layer 104A is formed from trimethylgallium (TMG), trimethylindium (TMI), phosphine (PH ₃ ), and arsine ( AsH ₃ ) is used as a raw material, and Ga _0.6 In _0.4 P constituting the barrier layer 1042A of the active layer 104A is formed using trimethyl gallium (TMG), trimethylindium (TMI), and phosphine (PH ₃ ) as raw materials. To do.

  As described above, the well layers 1041A of the resonator spacer layers 103A and 105A and the active layer 104A are made of AlGaInP and GaInPAs, respectively, so that the difference in band gap between the resonator spacer layers 103A and 105A and the well layer 1041A and the barrier layer The difference in band gap between 1042A and the well layer 1041A can be remarkably increased as compared with the prior art. As a result, the effect of confining carriers in the well layer 1041A is remarkably increased, and the surface emitting laser element 1A oscillates at a low threshold and radiates higher-power oscillation light.

  Further, since the active layer 104A contains GaInPAs having a compressive strain, the increase in gain is increased by band separation between heavy holes and light holes. As a result, high gain and high output oscillation light with a low threshold can be obtained. This effect cannot be obtained with a 780 nm or 850 nm surface emitting laser element made of an AlGaAs system having substantially the same lattice constant as the GaAs substrate.

  Furthermore, the improvement in carrier confinement and the increase in gain due to the active layer 104A having a strained quantum well structure reduce the threshold current of the surface-emitting laser element 1A, thereby reducing the reflectance by the reflective layer 106 on the light extraction side. It becomes possible, and the output can be further increased.

  Further, when the gain is increased, a decrease in light output due to the temperature rise of the surface emitting laser element 1A can be suppressed, and the element spacing of the surface emitting laser array 100 can be further reduced.

  Furthermore, since the active layer 104A is made of a material that does not contain Al, formation of a non-radiative recombination center can be suppressed by reducing oxygen uptake into these layers, thereby extending the lifetime. As a result, the writing unit or the light source unit can be reused.

  In the surface emitting laser array 100, the interval X3 may be set to be the same as the interval X1 or the interval X2.

[Embodiment 2]
FIG. 9 is a plan view of the surface emitting laser array according to the second embodiment. Referring to FIG. 9, surface emitting laser array 100A according to the second embodiment includes surface emitting laser elements 201-236.

  Two surface emitting laser elements 219, 226/211, 218, five surface emitting laser elements 203, 209, 216, 224, 231/204, 210, 217, 225, 232/205, 212, 220, 227, 233 and six surface emitting laser elements 201, 207, 214, 222, 229, 235/202, 208, 215, 223, 230, and 236 are arranged in the sub-scanning direction, and four surface emitting laser elements 201 to 201 are disposed. 204/233 to 236 and seven surface emitting laser elements 205 to 211/212 to 218/219 to 225/226 to 232 are arranged in the main scanning direction.

  Four surface emitting laser elements 201 to 204/233 to 236 and seven surface emitting laser elements 205 to 211/212 to 218/219 to 225/226 to 232 arranged in the main scanning direction are arranged in the sub scanning direction. Arranged staircases. As a result, the 36 laser beams emitted from the 36 surface emitting laser elements 201 to 236 do not overlap each other.

  The intervals between the four surface emitting laser elements 201 to 204/233 to 236 and the seven surface emitting laser elements 205 to 211/212 to 218/219 to 225/226 to 232 arranged in the main scanning direction are the main scanning. Evenly spaced in the direction, set to the distance X. The interval X is set to 30 μm, for example.

  Further, two surface emitting laser elements 219, 226/211, 218 and five surface emitting laser elements 203, 209, 216, 224, 231/204, 210, 217, 225, 232 arranged in the sub-scanning direction. / 205, 212, 220, 227, 233 and six surface emitting laser elements 201, 207, 214, 222, 229, 235/202, 208, 215, 223, 230, 236, two adjacent surface emitting lasers The interval between the elements is set to the interval d1 at the center of the surface emitting laser array 100A, and is set to the interval d2 at the peripheral portion. That is, the intervals between the surface emitting laser elements 212 and 220 / between 213 and 221/214 and 222/215 and 223/216 and 224/217 and 225 arranged at the center of the surface emitting laser array 100A are as follows. The surface emitting laser elements 201, 207/202, 208/203, 209/204, 210/227, 233/228, which are set to the distance d1 and are arranged in the peripheral portion of the surface emitting laser array 100A, The interval between 234/229, 235/230, 236 is set to the interval d2. Also, between the surface emitting laser elements 205, 212/206, 213/207, 214/208, 215/209, 216/210, 217/211, 218/219, 226/220, 227 The interval between / 221,228 / 222,229 / 223/230 / 224,231 / 225,232 is set to the interval d3 between the interval d1 and the interval d2.

  In this case, the interval d1 is set to be wider than the interval when 36 surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction, and the interval d2 is set to 36 surface emitting lasers. The interval is set smaller than the interval when the elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction. The distance d1 is set to 40 μm, for example, the distance d2 is set to 30 μm, for example, and the distance d3 is set to 35 μm, for example.

  The interval C in the sub-scanning direction of the four perpendicular lines L7 to L10 lowered from the four centers of the four surface emitting laser elements 201 to 204 arranged in the main scanning direction to the straight line 41 arranged in the sub-scanning direction is , Equally spaced.

  In addition, the sub-scanning direction of seven perpendicular lines drawn down from seven centers of the seven surface emitting laser elements 205 to 211/212 to 218/219 to 225/226 to 232 arranged in the main scanning direction on a straight line 41 The intervals at are also equal and are the same as the interval C.

  Further, the intervals in the sub-scanning direction of the four perpendicular lines dropped from the four centers of the four surface emitting laser elements 233 to 236 arranged in the main scanning direction to the straight line 41 arranged in the sub-scanning direction, etc. This is the interval and is the same as the interval C.

  In the surface emitting laser array 100A, since a plurality of surface emitting laser elements are arranged in eight rows in the main scanning direction, the interval C is d1 / 8 = 40/8 = 5 μm.

  Furthermore, in the surface emitting laser array 100A, the number of surface emitting laser elements arranged in the main scanning direction differs depending on the position in the sub scanning direction.

  Thus, in the surface emitting laser array 100A, the four surface emitting laser elements 201 to 204/233 to 236 and the seven surface emitting laser elements 205 to 211/212 to 218/219 arranged in the main scanning direction. ˜225 / 226˜232 are arranged at equal intervals X, and two surface emitting laser elements 219, 226/211, 218 and five surface emitting laser elements 203, 209, 216 arranged in the sub-scanning direction. 224, 231/204, 210, 217, 225, 232/205, 212, 220, 227, 233 and six surface emitting laser elements 201, 207, 214, 222, 229, 235/202, 208, 215, 223 , 230, 236 are arranged so as to become wider from the peripheral part to the central part of the surface emitting laser array 100A.

  That is, in the surface emitting laser array 100A, the two surface emitting laser elements 219, 226/211, 218 and the five surface emitting laser elements 203, 209, 216, 224, 231/204 arranged in the sub-scanning direction. , 210, 217, 225, 232/205, 212, 220, 227, 233 and six surface emitting laser elements 201, 207, 214, 222, 229, 235/202, 208, 215, 223, 230, 236 The interval is wider in the central part than in the peripheral part of the surface emitting laser array 100A, and varies depending on the position in the sub-scanning direction.

  As a specific example, the distance between the surface emitting laser elements 213 to 214 (peripheral part) is narrower than the distance between the surface emitting laser elements 215 to 221 (center part).

  As a result, the influence of heat generated from the surface emitting laser elements arranged in the peripheral portion of the surface emitting laser array 100A on the surface emitting laser elements arranged in the central portion is reduced, and the 36 pieces of the surface emitting laser array 100A are reduced. When the surface emitting laser elements 201 to 236 are simultaneously operated, the temperature distribution in the surface emitting laser array 100A is larger than that in the case where 36 surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction. It is made uniform. Therefore, the output characteristics of the 36 surface emitting laser elements can be made uniform. Since the temperatures of the surface emitting laser elements 214, 215, 222, and 223 having the highest temperature in the surface emitting laser array 100A are lowered, the life of the surface emitting laser array 100A can be extended.

  The interval X1 is set to be wider than the interval when 36 surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction, and the interval d2 is set to 36 Since the surface emitting laser elements are set to an interval narrower than the interval when the surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction, the area occupied by the surface emitting laser elements 201-236 is 36 surface emitting laser elements. Can be made smaller than when they are arranged at equal intervals in the sub-scanning direction and the main scanning direction. As a result, when the surface emitting laser array 100A is used as a light source for optical writing, 36 surface emitting laser elements are arranged at equal intervals in the sub-scanning direction and the main scanning direction with respect to aberrations of an optical system such as a collimating lens. It can be smaller than the case. And since the temperature rise of the surface emitting laser elements 214, 215, 222, and 223 near the center can be suppressed while the area of the surface emitting laser array 100A is reduced, the influence of the aberration of the optical system such as a lens can be suppressed. When the surface emitting laser array 100A is used in an image forming apparatus, a clear image is obtained and the life of the surface emitting laser array 100A can be extended, so that the optical writing optical unit itself can be reused, and the environmental load is reduced. Can contribute.

  FIG. 10 is another plan view of the surface emitting laser array according to the second embodiment. The surface emitting laser array according to the second embodiment may be a surface emitting laser array 100B shown in FIG.

  Referring to FIG. 10, surface emitting laser array 100 </ b> B moves surface emitting laser element 219 of surface emitting laser array 100 </ b> A shown in FIG. 9 to the lower side of surface emitting laser element 231, and between surface emitting laser elements 212 and 220. / 213, 221/214, 222/215, 223/216, 224/217, 225 is set to the interval d3, and the others are the same as those of the surface emitting laser array 100A. Also in the surface emitting laser array 100B, the same effect as the surface emitting laser array 100A can be enjoyed.

  Each of the surface emitting laser elements 201 to 236 shown in FIGS. 9 and 10 includes the surface emitting laser element 1 shown in FIGS. 2 and 3 or the surface emitting laser element 1A shown in FIGS.

  Others are the same as in the first embodiment.

[Embodiment 3]
FIG. 11 is a plan view of the surface emitting laser array according to the third embodiment. Referring to FIG. 11, surface emitting laser array 100 </ b> C according to Embodiment 3 includes surface emitting laser elements 301 to 336.

  In the surface emitting laser array 100C, in the surface emitting laser array 100A (see FIG. 9), the interval between the surface emitting laser elements in the main scanning direction is set to the interval X1 at the center of the surface emitting laser array 100A. This corresponds to the interval set at the interval X2.

  Therefore, in the surface emitting laser array 100C, the number of surface emitting laser elements arranged in the main scanning direction differs depending on the position in the sub scanning direction, and the number of surface emitting laser elements arranged in the sub scanning direction is different from that in the main scanning direction. It depends on the position of the direction.

  As described above, in the surface emitting laser array 100C, the spacing in the planar direction of the surface emitting laser elements disposed at the center is the surface emitting laser element disposed at the peripheral portion in both the main scanning direction and the sub scanning direction. It is wider than the interval in the plane direction.

  As a result, the influence of the heat generated from the surface emitting laser elements arranged in the peripheral portion on the surface emitting laser elements arranged in the central portion can be reduced as compared with the surface emitting laser arrays 100 and 100A. The characteristics of the 36 surface emitting laser elements 301 to 336 can be further uniformized. Further, since the temperatures of the surface emitting laser elements 314, 315, 322, and 323 that are the highest temperature in the surface emitting laser array 100B are lowered, the life of the surface emitting laser array 100B can be extended. Furthermore, since the temperature rise of the surface emitting laser elements 314, 315, 322, and 323 near the center can be suppressed while the area of the surface emitting laser array 100B is reduced, the influence of aberration of the optical system such as a lens can be suppressed. When the surface emitting laser array 100B is used in an image forming apparatus, a clear image is obtained and the life of the surface emitting laser array 100B can be extended, so that the optical writing optical unit itself can be reused, and the environmental load is reduced. Can contribute.

  FIG. 12 is another plan view of the surface emitting laser array according to the third embodiment. The surface emitting laser array according to the third embodiment may be a surface emitting laser array 100D shown in FIG.

  Referring to FIG. 12, surface emitting laser array 100D moves surface emitting laser element 319 of surface emitting laser array 100C shown in FIG. The distance between / 313, 321/314, 322/315, 323/316, 324/317, 325 is set to the distance d3, and the others are the same as those of the surface emitting laser array 100C. Also in the surface emitting laser array 100D, the same effect as the surface emitting laser array 100C can be enjoyed.

  Each of the surface emitting laser elements 301 to 336 shown in FIGS. 11 and 12 includes the surface emitting laser element 1 shown in FIGS. 2 and 3 or the surface emitting laser element 1A shown in FIGS.

  Others are the same as in the first embodiment.

[Embodiment 4]
FIG. 13 is a plan view of a surface emitting laser array according to the fourth embodiment. Referring to FIG. 13, surface emitting laser array 100E according to the fourth embodiment includes surface emitting laser elements 401-436.

  The surface emitting laser elements 401 to 436 are two-dimensionally arranged in 6 rows × 6 columns. And six surface emitting laser elements 401, 407, 413, 419, 425, 431/402, 408, 414, 420, 426, 432/403, 409, 415, 421, 427, 433/404, 410, 416 , 422, 428, 434/405, 411, 417, 423, 429, 435/406, 412, 418, 424, 430, 436 are arranged in a zigzag shape in the sub-scanning direction, and include six surface emitting laser elements 401. ˜406 / 407 to 412/413 to 418/414 to 424/425 to 430/431 to 436 are arranged in the main scanning direction.

  The six surface emitting laser elements 401 to 406/407 to 412/413 to 418/414 to 424/425 to 430/431 to 436 arranged in the main scanning direction are arranged stepwise in the sub scanning direction. Is done. As a result, the 36 laser beams emitted from the 36 surface emitting laser elements 401 to 436 do not overlap each other.

  In the six surface emitting laser elements 401 to 406/407 to 412/413 to 418/414 to 424/425 to 430/431 to 436 arranged in the main scanning direction, the distance between two adjacent surface emitting laser elements Is set to the interval X1 in the central portion of the surface emitting laser array 100C, and is set to the interval X2 in the peripheral portion. That is, the distance between the surface emitting laser elements 403, 404/409, 410/415, 416/421, 422/427, 428/433, 434 arranged at the center of the surface emitting laser array 100B is The surface emitting laser elements 401 and 402/405, 406/407, 408, 411, 412/413, 414/417, which are set to the interval X1 and arranged in the peripheral portion of the surface emitting laser array 100C, The interval between 418 / 419,420 / 423,424 / 425,426 / 429,430 / 431,432 / 435/436 is set to the interval X2. Also, between the surface emitting laser elements 402, 403/404, 405/408, 409/410, 411/414, 415/416, 417/420, 421/422, 423/426, 427 The interval between / 428, 429/432, 433/434, 435 is set to the interval X3 between the interval X1 and the interval X2.

  The interval C in the sub-scanning direction of the six vertical lines L11 to L16 drawn down from the six centers of the six surface emitting laser elements 401 to 406 arranged in the main scanning direction to the straight line 42 arranged in the sub-scanning direction is , Equally spaced and determined by C = d / 6.

  Six vertical surface light emitting laser elements 407 to 412/413 to 418/419 to 424/425 to 430/431 to 436 arranged in the main scanning direction are subordinates of six perpendicular lines drawn down to a straight line 42. The intervals in the scanning direction are also equal intervals and the same as the interval C.

  Each of the six surface emitting laser elements 401 to 406 arranged in the main scanning direction in the first row is adjacent to the six surface emitting laser elements 407 to 412 arranged in the main scanning direction in the second row. Between the two surface emitting laser elements.

  More specifically, the surface emitting laser element 401 is disposed between the surface emitting laser elements 407 and 408, the surface emitting laser element 402 is disposed between the surface emitting laser elements 408 and 409, and the surface emitting laser element 403 is The surface emitting laser element 404 is disposed between the surface emitting laser elements 410 and 411, and the surface emitting laser element 405 is disposed between the surface emitting laser elements 411 and 412. The

  Six surface emitting laser elements 407 to 412/413 to 418/419 to 424/425 to 430/431 to 436 arranged in the main scanning direction in other rows are also composed of the six surface emitting laser elements 401 to 406. Arranged in the same way.

  That is, in the surface-emitting laser array 100E, each of the plurality of surface-emitting laser elements arranged in the main scanning direction at the first position in the sub-scanning direction is adjacent to the first position in the sub-scanning direction. It is arranged between two adjacent surface emitting laser elements of a plurality of surface emitting laser elements arranged in the main scanning direction at the position.

  Further, the surface emitting laser array 100E includes six surface emitting laser elements arranged in the second row, the fourth row, and the sixth row on the paper surface in the surface emitting laser array 100 (see FIG. 1). In the surface emitting laser array shifted to the left side or the surface emitting laser array 100 (see FIG. 1), six surface emitting laser elements arranged in the first row, the third row, and the fifth row are arranged on the paper surface. Corresponds to a surface emitting laser array shifted to the right side in FIG.

  As a result, in the surface emitting laser array 100E, the interval W1 between the two surface emitting laser elements arranged in the central portion is wider than the interval W2 between the two surface emitting laser elements arranged in the peripheral portion.

  As described above, in the surface emitting laser array 100E, the spacing in the planar direction of the surface emitting laser elements arranged at the center is equal to the surface emitting laser elements arranged at the periphery in both the main scanning direction and the sub scanning direction. It is wider than the interval in the plane direction.

  As a result, the influence of the heat generated from the surface emitting laser elements arranged in the peripheral portion on the surface emitting laser elements arranged in the central portion can be reduced as compared with the surface emitting laser arrays 100 and 100A. Therefore, the characteristics of the 36 surface emitting laser elements 401 to 436 can be made more uniform. Since the temperatures of the surface emitting laser elements 415, 416, and 422 that are the highest temperature in the surface emitting laser array 100E are lowered, the life of the surface emitting laser array 100E can be extended. Further, since the temperature rise of the surface emitting laser elements 415, 416, and 422 near the center can be suppressed while the area of the surface emitting laser array 100E is reduced, the influence of aberration of the optical system such as a lens can be suppressed. When the light emitting laser array 100E is used in an image forming apparatus, a clear image can be obtained and the life of the surface emitting laser array 100E can be extended, so that the optical writing optical unit itself can be reused, contributing to a reduction in environmental load. .

  In the above, six surface emitting laser elements arranged in the first row, the third row and the fifth row, or six pieces arranged in the second row, the fourth row and the sixth row. However, the present invention is not limited to this, and the six surface-emitting laser elements arranged in each row may be shifted in different directions depending on the row.

  Others are the same as in the first embodiment.

[Embodiment 5]
FIG. 14 is a plan view of a surface emitting laser array according to the fifth embodiment. Referring to FIG. 14, surface emitting laser array 100 </ b> F according to Embodiment 5 includes surface emitting laser elements 501 to 536.

  Three surface emitting laser elements 513, 519, 525/512, 518, 524, and five surface emitting laser elements 501, 507, 521, 527, 533/502, 508, 515, 528, 534/503, 509 , 522, 529, 535/504, 510, 516, 530, 536/505, 511, 517, 523, 531/506, 514, 520, 526, 532 are arranged in the sub-scanning direction and have five surface light emission. The laser elements 501 to 505/532 to 536, the six surface emitting laser elements 513 to 518/519 to 524, and the seven surface emitting laser elements 506 to 512/525 to 531 are arranged in the main scanning direction.

  Five surface emitting laser elements 501 to 505/532 to 536, six surface emitting laser elements 513 to 518/519 to 524 and seven surface emitting laser elements 506 to 512/525 arranged in the main scanning direction. 531 are staggered in the sub-scanning direction. As a result, the 36 laser beams emitted from the 36 surface emitting laser elements 501 to 536 do not overlap each other.

  The intervals in the main scanning direction of the surface emitting laser elements 501 to 514, 516 to 521, 523 to 536 arranged in the peripheral portion of the surface emitting laser array 100F are equal intervals and set to the interval X.

  Further, in the central portion of the surface emitting laser array 100F, the spacing in the planar direction between the two adjacent surface emitting laser elements is wider than the spacing in the planar direction between the two adjacent surface emitting laser elements in the peripheral portion.

  Specifically, the distance between the surface emitting laser elements 503 to 504 (peripheral part) is narrower than the distance between the surface emitting laser elements 515 to 516 (center part).

  That is, in the surface emitting laser array 100F, a part of the surface emitting laser elements arranged at the center in the surface emitting laser array in which a plurality of surface emitting laser elements are arranged at equal intervals X in the main scanning direction is moved to the peripheral part. This corresponds to the surface emitting laser array.

  More specifically, the surface emitting laser array 100F includes the surface emitting laser elements 514 and 515, the surface emitting laser elements 515 and 516, the surface emitting laser elements 521 and 522, and the surface emitting laser elements 522 in the main scanning direction. This corresponds to a surface emitting laser array in which the surface emitting laser elements existing between 523 are moved to the periphery.

  As described above, in the surface emitting laser array 100F, the spacing in the plane direction of the surface emitting laser elements arranged at the center is equal to the surface emitting laser elements arranged at the periphery in both the main scanning direction and the sub scanning direction. It is wider than the interval in the plane direction.

  In other words, the density at which the surface emitting laser elements are arranged is sparser in the central portion than in the peripheral portion of the surface emitting laser array.

  As a result, the influence of the heat generated from the surface emitting laser elements arranged in the peripheral portion on the surface emitting laser elements arranged in the central portion can be reduced as compared with the surface emitting laser arrays 100 and 100A. Therefore, the characteristics of the 36 surface emitting laser elements 501 to 536 can be made more uniform. Since the temperatures of the surface emitting laser elements 515, 516 and 522 that are the highest temperature in the surface emitting laser array 100F are lowered, the lifetime of the surface emitting laser array 100F can be extended. Further, since the temperature rise of the surface emitting laser elements 515, 516 and 522 near the center can be suppressed while the area of the surface emitting laser array 100F is reduced, the influence of the aberration of the optical system such as a lens can be suppressed. When the light emitting laser array 100F is used in an image forming apparatus, a clear image is obtained, and the life of the surface emitting laser array 100F can be extended, so that the optical writing optical unit itself can be reused, which can contribute to reduction of environmental load. .

  In Embodiments 1 to 5 described above, the surface-emitting laser array including 36 surface-emitting laser elements has been described. However, in the present invention, the surface-emitting laser array according to the present invention is not limited to this. The surface emitting laser elements other than 36 may be provided, and the arrangement method thereof is free in the range having the intervals described in the first to fifth embodiments.

[Embodiment 6]
A surface emitting laser array according to the sixth embodiment will be described with reference to FIGS. This surface-emitting laser array has 40 surface-emitting laser elements, and a plurality of surface-emitting laser elements arranged in a line along a direction corresponding to the sub-scanning direction (hereinafter referred to as “S direction” for convenience). Eight element rows are arranged in a direction corresponding to the main scanning direction (hereinafter referred to as “M direction” for convenience).

  And 40 surface-emitting laser elements are equally spaced C in the S direction.

  Here, in order to distinguish each element row, for the sake of convenience, the first element row L1, the second element row L2, the third element row L3 from the left side to the right side of each drawing (FIGS. 15 to 18). , A fourth element row L4, a fifth element row L5, a sixth element row L6, a seventh element row L7, and an eighth element row L8.

  Regarding the M direction, the distance between the first element row L1 and the second element row L2 is X4, the distance between the second element row L2 and the third element row L3 is X3, and the third element row L3 and the fourth element row. The distance from L4 is X2, the distance between the fourth element row L4 and the fifth element row L5 is X1, the distance between the fifth element row L5 and the sixth element row L6 is X2, and the sixth element row L6 and the seventh element row. The interval between the columns L7 is X3, the interval between the seventh element column L7 and the eighth element column L8 is X4, and X1> X2> X3> X4. That is, the interval between two element rows that are located in the center of a plurality of rows and adjacent to each other is larger than the interval between two element rows that are located on the end side of the plurality of rows and adjacent to each other.

  FIG. 15 is a plan view of a surface emitting laser array 100G according to the sixth embodiment.

  In the surface emitting laser array 100G, eight element arrays each including five surface emitting laser elements arranged in a line at equal intervals d along the S direction are arranged in the M direction. That is, the number of element rows is larger than the number of surface emitting laser elements constituting one element row.

  In the two element rows adjacent to each other, the distance between the two closest surface emitting laser elements in the S direction is C.

  Specifically, X1 = 56 μm, X2 = 45 μm, X3 = 36 μm, X4 = 26 μm, d = 35.2 μm, and C = 4.4 μm. The interval d is smaller than the interval X1.

  In addition, although the space | interval d is larger than the space | interval X4, it is not limited to this. Since the peripheral part of the surface emitting laser array has less thermal interference and the temperature rise is smaller than that of the central part, the distance d should be smaller than the distance X1.

  FIG. 16 is a plan view of a surface emitting laser array 100H according to the sixth embodiment.

  In this case, the first element array L1 is composed of six surface emitting laser elements, the second element array L2 is composed of five surface emitting laser elements, and the third element array L3 is composed of four surface emitting laser elements. The fourth element array L4 is composed of five surface emitting laser elements, the fifth element array L5 is composed of five surface emitting laser elements, and the sixth element array L6 is composed of four surface elements. The seventh element array L7 is composed of five surface emitting laser elements, and the eighth element array L8 is composed of six surface emitting laser elements.

  In the two element rows adjacent to each other, the interval between the two adjacent surface emitting laser elements in the S direction is C.

  Further, the intervals between the plurality of surface emitting laser elements in each element row are not necessarily equal.

  Specifically, X1 = 50 μm, X2 = 45.5 μm, X3 = 38.5 μm, X4 = 26 μm, and C = 4.4 μm.

  In the surface-emitting laser array 100H, the element temperature (particularly the active layer temperature) near the center when operated by the array can be reduced as compared with the surface-emitting laser array 100G.

  FIG. 17 is a plan view of the surface emitting laser array 100I according to the sixth embodiment.

  In the surface emitting laser array 100I, eight element arrays each including five surface emitting laser elements arranged in a line at equal intervals d along the S direction are arranged in the M direction. That is, the number of element rows is larger than the number of surface emitting laser elements constituting one element row.

  In the two element rows adjacent to each other, the distance between the closest two surface emitting laser elements in the S direction is larger than C. That is, the surface emitting laser array 100H has a so-called staggered arrangement.

  In the surface emitting laser array 100I, the position of the surface emitting laser element located closest to the + S side in each element row is defined as the first element row L1 → the third element row L3 → the fifth element row L5 → the seventh element row L7 → Although it is shifted to the −S side in the order of the second element row L 2 → the fourth element row L 4 → the sixth element row L 6 → the eighth element row L 8, it is not limited to this. For example, FIG. As in the surface emitting laser array 100J shown, the position of the surface emitting laser element closest to the + S side in each element row is the first element row L1 → the seventh element row L7 → the third element row L3 → the fifth element row. You may shift to -S side in order of L5-> 2nd element row L2-> 8th element row L8-> 4th element row L4-> 6th element row L6. That is, the shift order may be random.

  In the surface-emitting laser array 100I and the surface-emitting laser array 100J, a plurality of surface-emitting laser elements can be arranged in a wider area than the surface-emitting laser array 100G and the surface-emitting laser array 100H. Can be reduced.

  As described above, in the sixth embodiment, 40 surface emitting laser elements are two-dimensionally arranged, and an element array including at least two surface emitting laser elements arranged in a line along the S direction is provided. , Eight rows are arranged in the M direction perpendicular to the S direction, and with respect to the M direction, the interval between two element rows located in the center of the eight rows and adjacent to each other is two adjacent to each other on the end side of the eight rows. It is larger than the interval between the element rows.

  As a result, when a plurality of surface emitting laser elements are operated simultaneously, the heat generated from the surface emitting laser elements arranged in the peripheral portion of the surface emitting laser array has an effect on the surface emitting laser elements arranged in the central portion. The temperature rise of the surface emitting laser element that is reduced and disposed in the center is reduced as compared with the case where a plurality of surface emitting laser elements are disposed at equal intervals in the S direction and the M direction. Therefore, the output characteristics of each surface emitting laser element can be made uniform. Further, since the temperature of the surface emitting laser element that is the highest temperature is lowered, the life of the surface emitting laser array can be extended.

  Further, with respect to the S direction, the 40 surface emitting laser elements are equally spaced, and the number of element rows is larger than the number of surface emitting laser elements constituting one element row. The interval between the surface emitting laser elements in the element direction in the element array is smaller than the maximum value of the intervals between the plurality of surface emitting laser elements in the M direction.

  As a result, it is possible to increase the writing density while reducing the influence of thermal interference between the surface emitting laser elements and securing a space necessary for passing the wiring of each surface emitting laser element.

  By the way, in the case where five element arrays composed of eight surface emitting laser elements arranged in a line at equal intervals d along the S direction are arranged in the M direction, if d = 35.2 μm. C = 35.2 / 5 = 7.04 μm. That is, it becomes larger than the interval C in the surface emitting laser array of the sixth embodiment.

  Next, a simulation result of temperature rise in the surface emitting laser array will be described.

  Actually, when the surface emitting laser element was driven at a constant current of 4.26 mA (voltage: about 2.55 V), the output was almost 1.7 mW in a single operation. The active layer temperature of the element in the vicinity of the center where the element temperature rises most due to the same thermal interference after being similarly injected into each element at room temperature is increased by about 78 ° C. when estimated from the shift amount of the oscillation wavelength. Was obtained experimentally.

  Therefore, each of the surface emitting lasers is simulated by assuming that all the 40 surface emitting laser elements have the same calorific value, and corrected to the active layer temperature of the element near the center where the element temperature rises most due to the thermal interference. The temperature distribution of the active layer of the device was derived.

(1) In the case where 10 element rows composed of four surface emitting laser elements arranged in a line at equal intervals d along the S direction are arranged in the M direction at equal intervals X as in the prior art ( (See FIG. 19):

  Here, d = 44 μm and X = 30 μm. Therefore, C = 4.4 μm.

  The result in this case is shown in FIG. The difference in the rising temperature of the 40 surface emitting laser elements is about 13 ° C., and it can be seen that the rising temperature is higher in the surface emitting laser element near the center.

(2) In the case of the surface emitting laser array 100G (see FIG. 21):

  Here, d = 35.2 μm, X1 = 50 μm, X2 = 46 μm, X3 = 38 μm, and X4 = 26 μm. Therefore, C = 4.4 μm.

  The result in this case is shown in FIG. The largest temperature increase is 75.1 ° C., which is lower than in the case of (1).

  In addition, when the element rows composed of four surface emitting laser elements arranged in a line at equal intervals d along the S direction are arranged at equal intervals in the M direction, the largest temperature rise is It was 77.6 ° C. It can be seen that unevenly arranging the element rows has the effect of lowering the maximum temperature.

(3) In the case of the surface emitting laser array 100H (see FIG. 23):

  X1 = 50 μm, X2 = 45.5 μm, X3 = 38.5 μm, X4 = 26 μm, and C = 4.4 μm.

  The result in this case is shown in FIG. The largest temperature rise is 74.5 ° C., and the temperature is further lowered than in the case of (2).

  In general, a surface emitting laser element has a life of about twice as long as the temperature is lowered by 10 ° C. Therefore, for example, a temperature drop of 3.5 ° C. can be expected to have a long life of about 30%.

  The calorific value (W) can be approximated by drive voltage (V) × current (I) −light output (W). In this simulation, the driving conditions of all the surface emitting laser elements are assumed to be the same, and the calorific values of all the surface emitting laser elements are the same. However, the light output actually decreases as the degree of thermal interference increases. . Therefore, it is expected that the surface emitting laser element near the center has a larger calorific value, and the temperature distribution is actually greatly increased from the calculation result. Therefore, the actual temperature reduction by devising the arrangement of the surface emitting laser elements in the surface emitting laser array should be significantly larger than the calculated value, and the effect of extending the life is extremely great.

  In the above embodiment, the case where the shape of each mesa portion of the surface emitting laser array is circular has been described. However, the present invention is not limited to this, and may be any shape such as an elliptical shape, a square shape, a rectangular shape, or a polygon other than a quadrangle. It may be a shape.

  Moreover, although the said embodiment demonstrated the case where a surface emitting laser element was arranged in 1 row along S direction, it is not restricted to this, At least 1 element in a row | line | column is another element in a row | line | column. The arrangement may be shifted as compared to the arrangement.

[Application example]
FIG. 25 shows a schematic configuration of a laser printer 500 according to an embodiment of the present invention.

  The laser printer 500 includes an optical scanning device 900, a photosensitive drum 605, a charging charger 902, a developing roller 903, a toner cartridge 904, a cleaning blade 905, a paper feeding tray 906, a paper feeding roller 907, a registration roller pair 908, and a transfer charger 911. A fixing roller 909, a paper discharge roller 912, a paper discharge tray 910, and the like.

  A photosensitive layer is formed on the surface of the photosensitive drum 605. That is, the surface of the photosensitive drum 605 is a scanned surface. Here, it is assumed that the photosensitive drum 605 rotates in the direction of the arrow in FIG.

  The charging charger 902, the developing roller 903, the transfer charger 911, and the cleaning blade 905 are disposed in the vicinity of the surface of the photosensitive drum 605, respectively. Further, with respect to the rotation direction of the photosensitive drum 605, the charging charger 902, the developing roller 903, the transfer charger 911, and the cleaning blade 905 are arranged in this order.

  The charging charger 902 charges the surface of the photosensitive drum 605 uniformly.

  The optical scanning device 900 irradiates the surface of the photosensitive drum 605 charged by the charging charger 902 with light modulated based on image information from a host device (for example, a personal computer). As a result, on the surface of the photosensitive drum 605, the charge disappears only in the portion irradiated with light, and a latent image corresponding to the image information is formed on the surface of the photosensitive drum 605. The latent image formed here moves in the direction of the developing roller 903 as the photosensitive drum 605 rotates. The configuration of the optical scanning device 900 will be described later.

  The toner cartridge 904 stores toner, and the toner is supplied to the developing roller 903. The amount of toner in the toner cartridge 904 is checked when the power is turned on or when printing is completed. When the remaining amount is low, a message prompting replacement of the toner cartridge 904 is displayed on a display unit (not shown).

  As the developing roller 903 rotates, the toner supplied from the toner cartridge 904 is charged and thinly and uniformly attached to the surface thereof. Further, the developing roller 903 has an electric field in the opposite direction between a charged portion (a portion not irradiated with light) and an uncharged portion (a portion irradiated with light) in the photosensitive drum 605. A voltage is generated to generate. By this voltage, the toner adhering to the surface of the developing roller 903 adheres only to the portion irradiated with the light on the surface of the photosensitive drum 605. That is, the developing roller 903 causes the toner to adhere to the latent image formed on the surface of the photosensitive drum 605 and visualizes the image information. Here, the latent image to which the toner is attached (hereinafter referred to as “toner image” for convenience) moves in the direction of the transfer charger 911 as the photosensitive drum 605 rotates.

  Recording paper 913 is stored in the paper feed tray 906. A paper feed roller 907 is disposed in the vicinity of the paper feed tray 906, and the paper feed roller 907 takes out the recording paper 913 one by one from the paper feed tray 906 and conveys it to the registration roller pair 908. The registration roller pair 908 is disposed in the vicinity of the transfer roller 911, temporarily holds the recording paper 913 taken out by the paper feed roller 907, and moves the recording paper 913 in accordance with the rotation of the photosensitive drum 605. It is sent out toward the gap between 605 and the transfer charger 911.

  A voltage having a polarity opposite to that of the toner is applied to the transfer charger 911 in order to electrically attract the toner on the surface of the photosensitive drum 605 to the recording paper 913. With this voltage, the toner image on the surface of the photosensitive drum 605 is transferred to the recording paper 913. The recording sheet 913 transferred here is sent to the fixing roller 909.

  In the fixing roller 909, heat and pressure are applied to the recording paper 913, whereby the toner is fixed on the recording paper 913. The recording paper 913 fixed here is sent to the paper discharge tray 910 via the paper discharge roller 912 and sequentially stacked on the paper discharge tray 910.

  The cleaning blade 905 removes toner remaining on the surface of the photosensitive drum 605 (residual toner). The removed residual toner is used again. The surface of the photosensitive drum 605 from which the residual toner has been removed returns to the position of the charging charger 902 again.

  Next, the configuration of the optical scanning device 900 will be described.

  As shown in FIG. 26, the optical scanning device 900 includes a light source unit 601, a cylindrical lens 602, a polygon mirror 603, a scanning lens 604, and the like.

  The light source unit 601 has a surface emitting laser array equivalent to any of the surface emitting laser arrays 100 and 100A to 100J.

  The cylindrical lens 602 forms an image of light from the light source unit 601 in the sub-scanning direction in the vicinity of the deflection reflection surface of the polygon mirror 603.

  The polygon mirror 603 has a hexahedral mirror, and each mirror serves as a deflection reflection surface. The polygon mirror 603 rotates at a constant speed around a rotation axis parallel to the sub-scanning direction.

  The scanning lens 604 collects the light deflected by the polygon mirror 603 on the surface of the photosensitive drum 605.

  For example, when the surface emitting laser array 100G is used, the interval C is 4.4 μm, and if the magnification of the optical system is about 1.2, high-density writing of 4800 dpi (dot / inch) can be performed. By the way, as in the conventional case, when 40 surface emitting laser elements are arranged at equal intervals and C = 7.04 μm, if the magnification of the optical system is about 0.75 times, 4800 dpi (dot / inch) is possible. It becomes. However, if the magnification of the optical system is small, a large amount of light is required, which is not preferable.

  Further, in each of the surface emitting laser arrays 100, 100A to 100J, the intervals of the plurality of perpendiculars drawn from the centers of the plurality of surface emitting laser elements to the straight line arranged in the sub-scanning direction are set to be equal intervals C. Thus, by adjusting the lighting timing of the plurality of surface emitting laser elements, the light source can be captured on the photosensitive member 605 in the same manner as when the light sources are arranged at equal intervals C in the sub-scanning direction. The spacing written in the sub-scanning direction can be adjusted by adjusting the element spacing C of the surface emitting laser element and the magnification of the optical system.

  For example, when the surface emitting laser array 100 is used, the interval C is 5 μm, and if the magnification of the optical system is 2.1, high density writing of 2400 dpi (dot / inch) can be performed. . Further, by increasing the number of surface emitting laser elements, by further reducing the distance C, or by reducing the magnification, it is possible to further increase the density and to apply a higher quality. Note that the writing interval in the main scanning direction can be easily controlled by the lighting timing of the light source.

  Since the light source unit 601 has a surface-emitting laser array equivalent to any of the surface-emitting laser arrays 100 and 100A to 100J, it is possible to achieve higher output than before. As a result, the laser printer 500 can perform image formation at a higher speed than before.

  As described above, according to the optical scanning device 900 according to the present embodiment, the light source unit 601 has the surface emitting laser array equivalent to any one of the surface emitting laser arrays 100 and 100A to 100J. It is possible to stably scan the scanning surface. In addition, a long life can be realized.

  In addition, the laser printer 500 according to this embodiment includes the optical scanning device 900 that can stably scan the surface to be scanned, and as a result, a high-quality image can be formed at high speed. It becomes.

  If the image forming speed is comparable to the conventional one, the number of surface emitting laser elements constituting the surface emitting laser array can be reduced, and the manufacturing yield of the surface emitting laser array is greatly improved. Cost reduction can be achieved.

  Further, even if the writing dot density increases, printing can be performed without reducing the printing speed.

  Furthermore, since the area occupied by the plurality of surface emitting laser elements can be made smaller and the temperature rise near the center can be suppressed, the influence of the aberration of the optical system can be suppressed and the image quality can be improved.

  Further, since the lifetime of the surface emitting laser array is long, the light source unit can be reused.

  By the way, for example, when a surface emitting laser array is used for a so-called writing optical unit, the writing optical unit is disposable when the lifetime of the surface emitting laser element is short. However, since the surface emitting laser array equivalent to any one of the surface emitting laser arrays 100 and 100A to 100J has a long life as described above, the surface emitting laser equivalent to any one of the surface emitting laser arrays 100 and 100A to 100J is used. The writing optical unit using the array can be reused. Therefore, promotion of resource protection and reduction of environmental load can be achieved. This also applies to other devices using a surface emitting laser array.

  In the above embodiment, the case of the laser printer 500 as the image forming apparatus has been described. However, the present invention is not limited to this. In short, an image forming apparatus including the optical scanning device 900 can form a high-quality image at high speed as a result.

  Even in an image forming apparatus that forms a multicolor image, a high-quality image can be formed at high speed by using an optical scanning device that supports color images.

  In this case, as shown in FIG. 27 as an example, a tandem color machine including a plurality of photosensitive drums may be used. The tandem color machine includes a black (K) photosensitive drum K1, a charger K2, a developing device K4, a cleaning unit K5, a transfer charging unit K6, a cyan (C) photosensitive drum C1, and a charger. C2, developing unit C4, cleaning unit C5, transfer charging unit C6, magenta (M) photosensitive drum M1, charging unit M2, developing unit M4, cleaning unit M5, transfer charging unit M6, yellow A photosensitive drum Y1 for (Y), a charger Y2, a developer Y4, a cleaning unit Y5, a transfer charging unit Y6, an optical scanning device 1010, a transfer belt T80, a fixing unit T30, and the like.

  In this case, the optical scanning device 1010 includes a surface emitting laser array for black, a surface emitting laser array for cyan, a surface emitting laser array for magenta, and a surface emitting laser array for yellow. Each surface emitting laser array is a surface emitting laser array equivalent to any one of the surface emitting laser arrays 100 and 100A to 100J.

  The light from the surface emitting laser array for black is irradiated to the photosensitive drum K1 through the scanning optical system for black, and the light from the surface emitting laser array for cyan passes through the scanning optical system for cyan. The light from the surface emitting laser array for magenta is irradiated to the photosensitive drum C1, and the light from the surface emitting laser array for yellow is irradiated to the photosensitive drum M1 through the magenta scanning optical system. The photosensitive drum Y1 is irradiated through the scanning optical system. Note that an optical scanning device 1010 may be provided for each color.

  Each photosensitive drum rotates in the direction of the arrow in FIG. 27, and a charger, a developer, a transfer charging unit, and a cleaning unit are arranged in the order of rotation. Each charger uniformly charges the surface of the corresponding photosensitive drum. The surface of the photosensitive drum charged by the charger is irradiated with light by the optical scanning device 1010, and an electrostatic latent image is formed on the photosensitive drum. Then, a toner image is formed on the surface of the photosensitive drum by the corresponding developing device. Further, the toner images of the respective colors are transferred onto the recording paper by the corresponding transfer charging means, and finally the image is fixed on the recording paper by the fixing means T30.

  In a tandem color machine, color misregistration of each color may occur due to mechanical accuracy or the like. However, since the optical scanning device 1010 has a high-density surface-emitting laser array, a surface-emitting laser element to be lit is selected. Thus, the correction accuracy of the color misregistration of each color can be improved.

  An image forming apparatus using a silver salt film as the image carrier may be used. In this case, a latent image is formed on the silver salt film by optical scanning, and this latent image can be visualized by a process equivalent to a developing process in a normal silver salt photographic process. Then, it can be transferred to photographic paper by a process equivalent to a printing process in a normal silver salt photographic process. Such an image forming apparatus can be implemented as an optical plate making apparatus or an optical drawing apparatus that draws a CT scan image or the like.

  Further, an image forming apparatus using a color developing medium (positive photographic paper) that develops color by the heat energy of a beam spot as an image carrier may be used. In this case, a visible image can be directly formed on the image carrier by optical scanning.

  Further, as long as the image forming apparatus includes a surface emitting laser array equivalent to any of the surface emitting laser arrays 100 and 100A to 100J, an image forming apparatus that does not include an optical scanning device may be used.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a surface emitting laser array capable of uniformizing the characteristics of a plurality of surface emitting laser elements when operated simultaneously in the array. Further, the present invention is applied to a surface emitting laser array capable of extending the life. Furthermore, the present invention is applied to an optical scanning apparatus and an image forming apparatus provided with a surface emitting laser array that can uniformize the characteristics of a plurality of surface emitting laser elements when operated simultaneously in the array. Furthermore, the present invention is applied to an optical scanning apparatus and an image forming apparatus provided with a surface emitting laser array capable of extending the life.

It is a top view of the surface emitting laser array by Embodiment 1 of this invention. It is a schematic sectional drawing of the surface emitting laser element shown in FIG. It is sectional drawing which shows the vicinity of the active layer of the surface emitting laser element shown in FIG. FIG. 3 is a first process diagram illustrating a method for manufacturing the surface emitting laser array shown in FIG. 1. FIG. 4 is a second process diagram illustrating a method for manufacturing the surface emitting laser array illustrated in FIG. 1. FIG. 6 is a third process diagram illustrating a method for manufacturing the surface emitting laser array illustrated in FIG. 1. It is another schematic sectional drawing of the surface emitting laser element shown in FIG. It is sectional drawing which shows the vicinity of the active layer of the surface emitting laser element shown in FIG. 6 is a plan view of a surface emitting laser array according to a second embodiment. FIG. FIG. 10 is another plan view of the surface emitting laser array according to the second embodiment. 6 is a plan view of a surface emitting laser array according to Embodiment 3. FIG. FIG. 10 is another plan view of the surface emitting laser array according to the third embodiment. FIG. 10 is a plan view of a surface emitting laser array according to a fourth embodiment. FIG. 10 is a plan view of a surface emitting laser array according to a fifth embodiment. FIG. 10 is a plan view of a surface emitting laser array according to a sixth embodiment. FIG. 20 is another plan view of the surface emitting laser array according to the sixth embodiment. FIG. 20 is another plan view of the surface emitting laser array according to the sixth embodiment. FIG. 20 is another plan view of the surface emitting laser array according to the sixth embodiment. It is a figure for demonstrating the surface emitting laser array (conventional example) for simulation. It is a figure for demonstrating the simulation result in the surface emitting laser array of FIG. It is a figure for demonstrating the surface emitting laser array (the 1) for simulation. It is a figure for demonstrating the simulation result in the surface emitting laser array of FIG. It is a figure for demonstrating the surface emitting laser array (the 2) for simulation. It is a figure for demonstrating the simulation result in the surface emitting laser array of FIG. It is a figure for demonstrating schematic structure of the laser printer which concerns on one Embodiment of this invention. It is the schematic which shows the optical scanning device in FIG. It is a figure for demonstrating schematic structure of a tandem color machine.

Explanation of symbols

1 to 36, 1A, 201 to 236, 301 to 336, 401 to 436, 501 to 536... Surface emitting laser element, 40 to 42... Straight line, 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H , 100I ... Surface emitting laser array, 101 ... substrate, 102,106 ... reflective layer, 103,103A, 105,105A ... resonator spacer layer, 104,104A ... active layer, 107 ... selective oxide layer, 108 ... contact layer, 109 ... SiO ₂ layer, 110 ... insulating resin, 111 ... p-side electrode, 112 ... n-side electrode, 120 ... resist pattern, 500 ... laser printer (image forming apparatus), 601 ... light source unit, 603 ... polygon mirror (deflection) 604... Scanning lens (scanning optical system) 605... Photosensitive drum (image carrier), 90 DESCRIPTION OF SYMBOLS 0 ... Optical scanning device, 1010 ... Optical scanning device, 1021, 1061 ... Low refractive index layer, 1022, 1062 ... High refractive index layer, 1023, 1063 ... Composition gradient layer, 1041, 1041A ... Well layer, 1042, 1042A ... Barrier Layer, K1 ... photosensitive drum (image carrier), C1 ... photosensitive drum (image carrier), M1 ... photosensitive drum (image carrier), Y1 ... photosensitive drum (image carrier).

Claims (17)

A surface emitting laser array Ru comprising a surface-emitting laser element of the multiple,
The plurality of surface emitting laser elements are two-dimensionally arranged such that a plurality of element arrays each including at least two surface emitting laser elements arranged in a first direction are arranged in a second direction perpendicular to the first direction. It is located in,
Before SL regarding the first direction, the plurality of surface emitting laser elements are equally spaced,
The distance in the first or second direction, the central portion is wide surface emitting laser array than in the peripheral portion of the surface emitting laser array of the surface emitting laser element before Kifuku number. 2. The surface-emitting laser array according to claim 1, wherein an interval between the at least two surface-emitting laser elements arranged in the first direction is wider in a central portion than in a peripheral portion of the surface-emitting laser array. The surface emitting laser array according to claim 2, wherein an interval between at least two surface emitting laser elements arranged in the first direction is further different depending on a position in the first direction. The spacing definitive in the second direction of the plurality of element array, a wide central portion than the peripheral portion of the surface emitting laser array, the surface emitting laser array according to claim 1. The interval definitive in the second direction, further, differs depending on the position in the second direction, the surface emitting laser array according to claim 4 wherein the plurality of element rows. The interval between the at least two surface emitting laser elements arranged in the first direction is wider at the center than at the periphery of the surface emitting laser array,
The spacing definitive in the second direction of the plurality of element array, a wide central portion than the peripheral portion of the surface emitting laser array, the surface emitting laser array according to claim 1. The interval between the at least two surface emitting laser elements arranged in the first direction is further different depending on the position in the first direction,
The interval definitive in the second direction, further, differs depending on the position in the second direction, the surface emitting laser array according to claim 6 of the plurality of element rows. The first direction is a sub-scanning direction when the surface emitting laser array is used in an optical scanning device,
The surface emitting laser array according to any one of claims 1 to 7 , wherein the second direction is a main scanning direction when the surface emitting laser array is used in an optical scanning device. A surface emitting laser array in which a plurality of surface emitting laser elements are two-dimensionally arranged,
A plurality of element rows composed of at least two surface emitting laser elements arranged along the first direction are arranged in a second direction perpendicular to the first direction,
The plurality of surface emitting laser elements are equally spaced with respect to the first direction,
With respect to the second direction, an interval between two element rows located in the center of the plurality of rows and adjacent to each other is larger than an interval between two element rows located on the end side of the plurality of rows and adjacent to each other.
The surface emitting laser array characterized in that the number of the element rows is larger than the number of surface emitting laser elements constituting one element row. Interval of the first direction about the surface emitting laser element in the element column of claim 9, wherein the smaller than the maximum value of the second interval of the plurality of surface emitting laser element with respect to the direction Surface emitting laser array. The plurality of columns includes a first column and a second column;
11. The surface-emitting laser array according to claim 9 , wherein the number of surface-emitting laser elements constituting the first row and the number of surface-emitting laser elements constituting the second row are different from each other. . In two element rows adjacent to each other among the plurality of rows, the interval between the two closest surface emitting laser elements in the first direction is different from the interval between the plurality of surface emitting laser devices in the first direction. The surface emitting laser array according to claim 9 , wherein A surface emitting laser array in which a plurality of surface emitting laser elements are two-dimensionally arranged,
The surface emitting laser array according to claim 1, wherein a density of the surface emitting laser elements arranged is sparser in a central portion than in a peripheral portion of the surface emitting laser array. An optical scanning device that scans a surface to be scanned with light,
A light source unit comprising the surface emitting laser array according to any one of claims 1 to 13 ;
A deflector for deflecting light from the light source unit;
A scanning optical system for condensing the light deflected by the polarizer on the surface to be scanned. At least one image carrier;
15. An image forming apparatus comprising: at least one optical scanning device according to claim 14 that scans the at least one image carrier with light including image information. The image forming apparatus according to claim 15 , wherein the image information is color image information. An image forming apparatus comprising the surface emitting laser array according to any one of claims 1 to 13 as a writing light source.